• Journal of the Korean GEO-environmental Society
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• v.24 no.12
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• pp.13-18
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• 2023

Cast-in-place concrete lining is commonly used in tunnel lining, but cast-in-place concrete lining has problems with construction and quality control. Precast segment lining is being used to solve these problems. In general, precast segment lining is known to have improved durability and easy maintenance such as rehabilitation of structures. This study compared the durability of 22 tunnel linings constructed with precast segments or cast-in-place reinforced concrete.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2008.04a
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• pp.624-629
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• 2008

When TBM excavates a tunnel, existing concrete lining segments are used as supporting structures for driving force. Axial stress on the lining segments are apt to be large in case of direct driving force. However, it drastically decline as it is farther and father from TBM and later, it tends to converge after a certain point. Such tendencies show similar results of finite element analysis. At the initial intervals, the values of finite element analysis are larger, while at the later intervals, the actual stress values are larger. It concludes that such tendencies are attributable to that the concrete lining segments have partially burst and cracked in the axial direction at the initial intervals. And differences of stresses at the later intervals are created by the changed plasticity of ground and the friction on the external sides of the lining segments.

• Journal of Korean Tunnelling and Underground Space Association
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• v.26 no.3
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• pp.255-280
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• 2024

If there are concerns about the stability of segment lining due to section deficiency or large deformation in shield TBM tunnel, reinforcement can be done through ground grouting outside the tunnel or by using steel plate reinforcement, ring beam reinforcement, or inner double layer lining inside the tunnel. Traditional analyses of shield TBM tunnels have been conducted using a continuum method that does not consider the segmented nature of segment lining. This study investigates the reinforcement mechanism for double layer reinforced sections with internal steel linings. By improving the modeling of segment lining, this study applies Break-joint mode (BJM), which considers the segmented characteristics of segment lining, to analyze the deformation characteristics of double layer reinforced sections. The results indicate that the existing concrete segment lining functioned similarly to ground reinforcement around the tunnel, rather than distribution the load. In general, both the BJM model considering the segmentation of segment lining and the continuum rigid method were similar deformation shapes and stress distributions of the lining under load. However, in terms of deformation, when the load strength exceeded the threshold, the deformation patterns of the two models differed.

• Journal of Korean Tunnelling and Underground Space Association
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• v.19 no.6
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• pp.905-913
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• 2017

To design segment lining, loads such as self weight, vertical load, horizontal load, ground reaction, water pressure, backfill grouting pressure et al. have to be considered. Earth pressure and water pressure are the major factor to design segment lining such as concrete strength, segment thickness and amount of rebar et al. To analysis earth pressure and water pressure acting on segment lining, filed monitoring and back analysis are performed in this study.

• Steel and Composite Structures
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• v.24 no.4
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• pp.481-497
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• 2017

In this paper, full-scale loading tests were performed on a rectangular segmental tunnel lining, which was assembled by steel composite segments, to investigate its load-bearing structural behavior and failure mechanism. The tests were also used to confirm the composite effect by adding concrete inside to satisfy the required performance under severe loading conditions. The design of the tested rectangular segmental lining and the loading scheme are also described to better understand the bearing capacity of this composite lining structure. It is found that the structural ultimate bearing capacity is governed by the bond capacity between steel plates and the tunnel segment. The failure of the strengthened lining is the consequence of local failure of the bond at waist joints. This led to a fast decrease of the overall stiffness and eventually a loss of the structural integrity.

• Journal of Korean Tunnelling and Underground Space Association
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• v.14 no.5
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• pp.547-559
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• 2012

The concrete structural design in domestic has based on the allowable stress design (ASD) method and ultimate strength design (USD) method. Recently limit state design (LSD) method has issued and attempted to adopt in geotechnical design. Because ASD method and USD method have restriction in economic design. In this study, the generated member forces were calculated about high strength concrete segment lining based on japanese LSD code. And it compared with domestic USD code for identifying the economic design possibility of LSD and domestic applicability. In analysis results, the aspect of moment had generated similarly each other but the member forces of japanese LSD code were decreased (26.0% of moment and 26.7% of shear force) comparing with USD method. For that reason, possibility of economic segment design with stable condition were identified.

• Structural Engineering and Mechanics
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• v.45 no.3
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• pp.337-354
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• 2013

For shield TBM (Tunnel Boring Machine) tunnel lining, the segment joint is the most critical component for determining the mechanical response of the complete lining ring. To investigate the mechanical behavior of the segment joint in a water conveyance tunnel, which is different from the vehicle tunnel because of the external loads and the high internal water pressure during the tunnel's service life, full-scale joint tests were conducted. The main advantage of the joint tests over previous ones was the definiteness of the loads applied to the joints using a unique testing facility and the acquisition of the mechanical behavior of actual joints. Furthermore, based on the test results and the theoretical analysis, a mechanical model of segment joints has been proposed, which consists of all important influencing factors, including the elastic-plastic behavior of concrete, the pre-tightening force of the bolts and the deformations of all joint components, i.e., concrete blocks, bolts and cast iron panels. Finally, the proposed mechanical model of segment joints has been verified by the aforementioned full-scale joint tests.

• Journal of Korean Tunnelling and Underground Space Association
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• v.23 no.2
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• pp.93-106
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• 2021

In general, segment lining tunnel refers to a tunnel formed by connecting precast concrete segments as a ring and connecting such rings to each other in the longitudinal direction of the tunnel. As the structural properties of the segment lining is highly dependent on the behavior of the segment joints, thus correct modelling of joint behavior is crucial to understand and design the segment tunnel lining. When the tunnel is subjected to ground loads, the segment joint behaves like a hinge that resists rotation, and when the induced moment exceeds a certain limit of the rotation then it may enter into non-linear field. In understanding the effect of the segment joint on the lining behavior, a moment-rotation relationship of the segment joint was explored based on the Japanese practice and Janssen's approach commonly used in the actual design. This study also presents a method to determine the rotational stiffness of joint refer to the bearing strength. The rotation of the segment joint was estimated in virtual design conditions based on the existing models and the proposed method. And the sectional force of the segment lining and joint were calculated along with the estimated rotation. As the rotation at the segment joint increases, the joint contact area decreases, so the designer have to verify the segment joint for bearing strength as well. This paper suggests a consistent method to determine the rotational stiffness and bearing strength of joints.

• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.6
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• pp.1125-1146
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• 2018

Segment lining applied to the TBM tunnel is mainly made of concrete, and it requires sufficient structural capacity to resist loads received during the construction and also after the completion. When segment lining is design to the Limit State Design, both Ultimate Limit State (ULS) and Service Limit State (SLS) should be met for the possible load cases that covers both permanent and temporary load cases - such as load applied by TBM. When design segment lining, it is important to check structural capacity at the joints as both temporary and permanent loads are always transferred through the segment joints, and sometimes the load applied to the joint is high enough to damage the segment - so called bursting failure. According to the various design guides from UK (PAS 8810, 2016), compression stress at the joint surface can generate bursting failure of the segment. This is normally from the TBM's jacking force applied at the circumferential joint, and the lining's hoop thrust generated from the permanent loads applied at the radial joint. Therefore, precast concrete segment lining's joints shall be designed to have sufficient structural capacity to resist bursting stresses generated by the TBM's jacking force and by the hoop thrust. In this study, bursting stress at the segment joints are calculated, and the joint's structural capacity was assessed using Leonhardt (1964) and FEM analysis for three different design cases. For those three analysis cases, hoop thrust at the radial joint was calculated with the application of the most widely used limit state design codes Eurocode and AASHTO LRFD (2017). For the circumferential joints bursting design, an assumed TBM jack force was used with considering of the construction tolerance of the segments and the eccentricity of the jack's position. The analysis results show reinforcement is needed as joint bursting stresses exceeds the allowable tensile strength of concrete. This highlights that joint bursting check shall be considered as a mandatory design item in the limit state design of the segment lining.

• Journal of Korean Tunnelling and Underground Space Association
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• v.25 no.2
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• pp.121-139
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• 2023

Various tunnels such as road, subway, and railway are under construction and operation. Various types of linings are used for structural stability of tunnel structures, and concrete segment linings are mainly installed in TBM tunnel construction. In this paper, when a fire occurs in a tunnel, the impact on the concrete segment lining, which is the structure in the tunnel, and related standards, fire resistance evaluation and fire resistance method are investigated through literature review and related contents are presented. Through this, it is intended to provide an information for practitioners to secure the safety of concrete segment linings against tunnel fires.